PROFIBUS Diagnostics

Devices for supporting bus-diagnostics

The SIMATIC ET 200 I/O systems offer powerful, multi-level diagnostic systems within the framework of Totally Integrated Automation for faults that occur in the control system (system diagnostics). System faults are automatically detected and are caught by programmable exception handling routines. Furthermore, such system faults are signaled to the connected HMI system, and displayed there in an appropriate manner.

In addition to system-wide diagnostics, Profibus offers so-called bus diagnostics which is supported by diagnostic devices.

Diagnostics Repeater

The diagnostics repeater for PROFIBUS DP connects PROFIBUS DP segments with RS 485 technology. It also physically monitors the copper bus lines in online mode.

If an error occurs, it sends a diagnostic message to the DP master with detailed information on the type and location of the error. The diagnostics repeater is a standard slave. It can be operated on any DP master that supports the standard RD_REC and WR_REC services. To record the topology, you will need either STEP 7 or COM PROFIBUS.

The following errors are diagnosed:

  • Break in signal lines A or B

  • Short circuit of signal lines A or B on the shield

  • Absent terminating resistors

  • Impermissible cascading depth

  • Too many stations in a segment

  • Station too far from the diagnostics repeater

  • Faulty messages

Sporadic errors are also detected. The error messages are displayed graphically in STEP 7 and COM PROFIBUS. They are completely integrated in the SIMATIC system diagnostics (e.g. overview diagnostics, "Report system error" function).